/*
 * (C) Copyright 2000-2004
 * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

/*
 * Serial up- and download support
 */
#include <common.h>
#include <command.h>
#include <s_record.h>
#include <net.h>
#include <exports.h>
#include <xyzModem.h>

DECLARE_GLOBAL_DATA_PTR;

#if (CONFIG_COMMANDS & CFG_CMD_LOADB)
/* support xmodem, www.embedsky.net */
static ulong load_serial_xmodem (ulong offset);
static ulong load_serial_ymodem (ulong offset);
#endif

#if (CONFIG_COMMANDS & CFG_CMD_LOADS)
static ulong load_serial (ulong offset);
static int read_record (char *buf, ulong len);
# if (CONFIG_COMMANDS & CFG_CMD_SAVES)
static int save_serial (ulong offset, ulong size);
static int write_record (char *buf);
# endif /* CFG_CMD_SAVES */

static int do_echo = 1;
#endif /* CFG_CMD_LOADS */

/* -------------------------------------------------------------------- */

#if (CONFIG_COMMANDS & CFG_CMD_LOADS)
int do_load_serial (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
    ulong offset = 0;
    ulong addr;
    int i;
    char *env_echo;
    int rcode = 0;
#ifdef  CFG_LOADS_BAUD_CHANGE
    int load_baudrate, current_baudrate;

    load_baudrate = current_baudrate = gd->baudrate;
#endif

    if (((env_echo = getenv("loads_echo")) != NULL) && (*env_echo == '1')) {
        do_echo = 1;
    } else {
        do_echo = 0;
    }

#ifdef  CFG_LOADS_BAUD_CHANGE
    if (argc >= 2) {
        offset = simple_strtoul(argv[1], NULL, 16);
    }
    if (argc == 3) {
        load_baudrate = (int)simple_strtoul(argv[2], NULL, 10);

        /* default to current baudrate */
        if (load_baudrate == 0)
            load_baudrate = current_baudrate;
    }
    if (load_baudrate != current_baudrate) {
        printf ("## Switch baudrate to %d bps and press ENTER ...\n",
            load_baudrate);
        udelay(50000);
        gd->baudrate = load_baudrate;
        serial_setbrg ();
        udelay(50000);
        for (;;) {
            if (getc() == '\r')
                break;
        }
    }
#else   /* ! CFG_LOADS_BAUD_CHANGE */
    if (argc == 2) {
        offset = simple_strtoul(argv[1], NULL, 16);
    }
#endif  /* CFG_LOADS_BAUD_CHANGE */

    printf ("## Ready for S-Record download ...\n");

    addr = load_serial (offset);

    /*
     * Gather any trailing characters (for instance, the ^D which
     * is sent by 'cu' after sending a file), and give the
     * box some time (100 * 1 ms)
     */
    for (i=0; i<100; ++i) {
        if (tstc()) {
            (void) getc();
        }
        udelay(1000);
    }

    if (addr == ~0) {
        printf ("## S-Record download aborted\n");
        rcode = 1;
    } else {
        printf ("## Start Addr      = 0x%08lX\n", addr);
        load_addr = addr;
    }

#ifdef  CFG_LOADS_BAUD_CHANGE
    if (load_baudrate != current_baudrate) {
        printf ("## Switch baudrate to %d bps and press ESC ...\n",
            current_baudrate);
        udelay (50000);
        gd->baudrate = current_baudrate;
        serial_setbrg ();
        udelay (50000);
        for (;;) {
            if (getc() == 0x1B) /* ESC */
                break;
        }
    }
#endif
    return rcode;
}

static ulong
load_serial (ulong offset)
{
    char    record[SREC_MAXRECLEN + 1]; /* buffer for one S-Record  */
    char    binbuf[SREC_MAXBINLEN];     /* buffer for binary data   */
    int binlen;             /* no. of data bytes in S-Rec.  */
    int type;               /* return code for record type  */
    ulong   addr;               /* load address from S-Record   */
    ulong   size;               /* number of bytes transferred  */
    char    buf[32];
    ulong   store_addr;
    ulong   start_addr = ~0;
    ulong   end_addr   =  0;
    int line_count =  0;

    while (read_record(record, SREC_MAXRECLEN + 1) >= 0) {
        type = srec_decode (record, &binlen, &addr, binbuf);

        if (type < 0) {
            return (~0);        /* Invalid S-Record     */
        }

        switch (type) {
        case SREC_DATA2:
        case SREC_DATA3:
        case SREC_DATA4:
            store_addr = addr + offset;
#ifndef CFG_NO_FLASH
            if (addr2info(store_addr)) {
            int rc;

            rc = flash_write((char *)binbuf,store_addr,binlen);
            if (rc != 0) {
                flash_perror (rc);
                return (~0);
            }
            } else
#endif
            {
            memcpy ((char *)(store_addr), binbuf, binlen);
            }
            if ((store_addr) < start_addr)
            start_addr = store_addr;
            if ((store_addr + binlen - 1) > end_addr)
            end_addr = store_addr + binlen - 1;
            break;
        case SREC_END2:
        case SREC_END3:
        case SREC_END4:
            udelay (10000);
            size = end_addr - start_addr + 1;
            printf ("\n"
                "## First Load Addr = 0x%08lX\n"
                "## Last  Load Addr = 0x%08lX\n"
                "## Total Size      = 0x%08lX = %ld Bytes\n",
                start_addr, end_addr, size, size
            );
            flush_cache (start_addr, size);
            sprintf(buf, "%lX", size);
            setenv("filesize", buf);
            return (addr);
        case SREC_START:
            break;
        default:
            break;
        }
        if (!do_echo) { /* print a '.' every 100 lines */
            if ((++line_count % 100) == 0)
                putc ('.');
        }
    }

    return (~0);            /* Download aborted     */
}

static int
read_record (char *buf, ulong len)
{
    char *p;
    char c;

    --len;  /* always leave room for terminating '\0' byte */

    for (p=buf; p < buf+len; ++p) {
        c = getc();     /* read character       */
        if (do_echo)
            putc (c);   /* ... and echo it      */

        switch (c) {
        case '\r':
        case '\n':
            *p = '\0';
            return (p - buf);
        case '\0':
        case 0x03:          /* ^C - Control C       */
            return (-1);
        default:
            *p = c;
        }

        /* Check for the console hangup (if any different from serial) */
        if (gd->jt[XF_getc] != getc) {
        if (ctrlc()) {
            return (-1);
        }
        }
    }

    /* line too long - truncate */
    *p = '\0';
    return (p - buf);
}

#if (CONFIG_COMMANDS & CFG_CMD_SAVES)

int do_save_serial (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
    ulong offset = 0;
    ulong size   = 0;
#ifdef  CFG_LOADS_BAUD_CHANGE
    int save_baudrate, current_baudrate;

    save_baudrate = current_baudrate = gd->baudrate;
#endif

    if (argc >= 2) {
        offset = simple_strtoul(argv[1], NULL, 16);
    }
#ifdef  CFG_LOADS_BAUD_CHANGE
    if (argc >= 3) {
        size = simple_strtoul(argv[2], NULL, 16);
    }
    if (argc == 4) {
        save_baudrate = (int)simple_strtoul(argv[3], NULL, 10);

        /* default to current baudrate */
        if (save_baudrate == 0)
            save_baudrate = current_baudrate;
    }
    if (save_baudrate != current_baudrate) {
        printf ("## Switch baudrate to %d bps and press ENTER ...\n",
            save_baudrate);
        udelay(50000);
        gd->baudrate = save_baudrate;
        serial_setbrg ();
        udelay(50000);
        for (;;) {
            if (getc() == '\r')
                break;
        }
    }
#else   /* ! CFG_LOADS_BAUD_CHANGE */
    if (argc == 3) {
        size = simple_strtoul(argv[2], NULL, 16);
    }
#endif  /* CFG_LOADS_BAUD_CHANGE */

    printf ("## Ready for S-Record upload, press ENTER to proceed ...\n");
    for (;;) {
        if (getc() == '\r')
            break;
    }
    if(save_serial (offset, size)) {
        printf ("## S-Record upload aborted\n");
    } else {
        printf ("## S-Record upload complete\n");
    }
#ifdef  CFG_LOADS_BAUD_CHANGE
    if (save_baudrate != current_baudrate) {
        printf ("## Switch baudrate to %d bps and press ESC ...\n",
            (int)current_baudrate);
        udelay (50000);
        gd->baudrate = current_baudrate;
        serial_setbrg ();
        udelay (50000);
        for (;;) {
            if (getc() == 0x1B) /* ESC */
                break;
        }
    }
#endif
    return 0;
}

#define SREC3_START             "S0030000FC\n"
#define SREC3_FORMAT            "S3%02X%08lX%s%02X\n"
#define SREC3_END               "S70500000000FA\n"
#define SREC_BYTES_PER_RECORD   16

static int save_serial (ulong address, ulong count)
{
    int i, c, reclen, checksum, length;
    char *hex = "0123456789ABCDEF";
    char    record[2*SREC_BYTES_PER_RECORD+16]; /* buffer for one S-Record  */
    char    data[2*SREC_BYTES_PER_RECORD+1];    /* buffer for hex data  */

    reclen = 0;
    checksum  = 0;

    if(write_record(SREC3_START))           /* write the header */
        return (-1);
    do {
        if(count) {                     /* collect hex data in the buffer  */
            c = *(volatile uchar*)(address + reclen);   /* get one byte    */
            checksum += c;                          /* accumulate checksum */
            data[2*reclen]   = hex[(c>>4)&0x0f];
            data[2*reclen+1] = hex[c & 0x0f];
            data[2*reclen+2] = '\0';
            ++reclen;
            --count;
        }
        if(reclen == SREC_BYTES_PER_RECORD || count == 0) {
            /* enough data collected for one record: dump it */
            if(reclen) {    /* build & write a data record: */
                /* address + data + checksum */
                length = 4 + reclen + 1;

                /* accumulate length bytes into checksum */
                for(i = 0; i < 2; i++)
                    checksum += (length >> (8*i)) & 0xff;

                /* accumulate address bytes into checksum: */
                for(i = 0; i < 4; i++)
                    checksum += (address >> (8*i)) & 0xff;

                /* make proper checksum byte: */
                checksum = ~checksum & 0xff;

                /* output one record: */
                sprintf(record, SREC3_FORMAT, length, address, data, checksum);
                if(write_record(record))
                    return (-1);
            }
            address  += reclen;  /* increment address */
            checksum  = 0;
            reclen    = 0;
        }
    }
    while(count);
    if(write_record(SREC3_END)) /* write the final record */
        return (-1);
    return(0);
}

static int
write_record (char *buf)
{
    char c;

    while((c = *buf++))
        putc(c);

    /* Check for the console hangup (if any different from serial) */

    if (ctrlc()) {
        return (-1);
    }
    return (0);
}
# endif /* CFG_CMD_SAVES */

#endif  /* CFG_CMD_LOADS */


#if (CONFIG_COMMANDS & CFG_CMD_LOADB)  /* loadb command (load binary) included */

#define XON_CHAR        17
#define XOFF_CHAR       19
#define START_CHAR      0x01
#define ETX_CHAR    0x03
#define END_CHAR        0x0D
#define SPACE           0x20
#define K_ESCAPE        0x23
#define SEND_TYPE       'S'
#define DATA_TYPE       'D'
#define ACK_TYPE        'Y'
#define NACK_TYPE       'N'
#define BREAK_TYPE      'B'
#define tochar(x) ((char) (((x) + SPACE) & 0xff))
#define untochar(x) ((int) (((x) - SPACE) & 0xff))

extern int os_data_count;
extern int os_data_header[8];

static void set_kerm_bin_mode(unsigned long *);
static int k_recv(void);
static ulong load_serial_bin (ulong offset);


char his_eol;        /* character he needs at end of packet */
int  his_pad_count;  /* number of pad chars he needs */
char his_pad_char;   /* pad chars he needs */
char his_quote;      /* quote chars he'll use */

int do_load_serial_bin (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
    ulong offset = 0;
    ulong addr;
    int load_baudrate, current_baudrate;
    int rcode = 0;
    char *s;

    /* pre-set offset from CFG_LOAD_ADDR */
    offset = CFG_LOAD_ADDR;

    /* pre-set offset from $loadaddr */
    if ((s = getenv("loadaddr")) != NULL) {
        offset = simple_strtoul(s, NULL, 16);
    }

    load_baudrate = current_baudrate = gd->baudrate;

    if (argc >= 2) {
        offset = simple_strtoul(argv[1], NULL, 16);
    }
    if (argc == 3) {
        load_baudrate = (int)simple_strtoul(argv[2], NULL, 10);

        /* default to current baudrate */
        if (load_baudrate == 0)
            load_baudrate = current_baudrate;
    }

    if (load_baudrate != current_baudrate) {
        printf ("## Switch baudrate to %d bps and press ENTER ...\n",
            load_baudrate);
        udelay(50000);
        gd->baudrate = load_baudrate;
        serial_setbrg ();
        udelay(50000);
        for (;;) {
            if (getc() == '\r')
                break;
        }
    }

    /* support xmodem, www.embedsky.net */
    if (strcmp(argv[0],"loadx")==0) {
        printf ("## Ready for binary (xmodem) download "
            "to 0x%08lX at %d bps...\n",
            offset,
            load_baudrate);

        addr = load_serial_xmodem (offset);

    } else if (strcmp(argv[0],"loady")==0) {
        printf ("## Ready for binary (ymodem) download "
            "to 0x%08lX at %d bps...\n",
            offset,
            load_baudrate);

        addr = load_serial_ymodem (offset);

    } else {

        printf ("## Ready for binary (kermit) download "
            "to 0x%08lX at %d bps...\n",
            offset,
            load_baudrate);
        addr = load_serial_bin (offset);

        if (addr == ~0) {
            load_addr = 0;
            printf ("## Binary (kermit) download aborted\n");
            rcode = 1;
        } else {
            printf ("## Start Addr      = 0x%08lX\n", addr);
            load_addr = addr;
        }
    }
    if (load_baudrate != current_baudrate) {
        printf ("## Switch baudrate to %d bps and press ESC ...\n",
            current_baudrate);
        udelay (50000);
        gd->baudrate = current_baudrate;
        serial_setbrg ();
        udelay (50000);
        for (;;) {
            if (getc() == 0x1B) /* ESC */
                break;
        }
    }

#ifdef CONFIG_AUTOSCRIPT
    if (load_addr) {
        char *s;

        if (((s = getenv("autoscript")) != NULL) && (strcmp(s,"yes") == 0)) {
            printf("Running autoscript at addr 0x%08lX ...\n", load_addr);
            rcode = autoscript (load_addr);
        }
    }
#endif
    return rcode;
}


static ulong load_serial_bin (ulong offset)
{
    int size, i;
    char buf[32];

    set_kerm_bin_mode ((ulong *) offset);
    size = k_recv ();

    /*
     * Gather any trailing characters (for instance, the ^D which
     * is sent by 'cu' after sending a file), and give the
     * box some time (100 * 1 ms)
     */
    for (i=0; i<100; ++i) {
        if (tstc()) {
            (void) getc();
        }
        udelay(1000);
    }

    flush_cache (offset, size);

    printf("## Total Size      = 0x%08x = %d Bytes\n", size, size);
    sprintf(buf, "%X", size);
    setenv("filesize", buf);

    return offset;
}

void send_pad (void)
{
    int count = his_pad_count;

    while (count-- > 0)
        putc (his_pad_char);
}

/* converts escaped kermit char to binary char */
char ktrans (char in)
{
    if ((in & 0x60) == 0x40) {
        return (char) (in & ~0x40);
    } else if ((in & 0x7f) == 0x3f) {
        return (char) (in | 0x40);
    } else
        return in;
}

int chk1 (char *buffer)
{
    int total = 0;

    while (*buffer) {
        total += *buffer++;
    }
    return (int) ((total + ((total >> 6) & 0x03)) & 0x3f);
}

void s1_sendpacket (char *packet)
{
    send_pad ();
    while (*packet) {
        putc (*packet++);
    }
}

static char a_b[24];
void send_ack (int n)
{
    a_b[0] = START_CHAR;
    a_b[1] = tochar (3);
    a_b[2] = tochar (n);
    a_b[3] = ACK_TYPE;
    a_b[4] = '\0';
    a_b[4] = tochar (chk1 (&a_b[1]));
    a_b[5] = his_eol;
    a_b[6] = '\0';
    s1_sendpacket (a_b);
}

void send_nack (int n)
{
    a_b[0] = START_CHAR;
    a_b[1] = tochar (3);
    a_b[2] = tochar (n);
    a_b[3] = NACK_TYPE;
    a_b[4] = '\0';
    a_b[4] = tochar (chk1 (&a_b[1]));
    a_b[5] = his_eol;
    a_b[6] = '\0';
    s1_sendpacket (a_b);
}


/* os_data_* takes an OS Open image and puts it into memory, and
   puts the boot header in an array named os_data_header

   if image is binary, no header is stored in os_data_header.
*/
void (*os_data_init) (void);
void (*os_data_char) (char new_char);
static int os_data_state, os_data_state_saved;
int os_data_count;
static int os_data_count_saved;
static char *os_data_addr, *os_data_addr_saved;
static char *bin_start_address;
int os_data_header[8];
static void bin_data_init (void)
{
    os_data_state = 0;
    os_data_count = 0;
    os_data_addr = bin_start_address;
}
static void os_data_save (void)
{
    os_data_state_saved = os_data_state;
    os_data_count_saved = os_data_count;
    os_data_addr_saved = os_data_addr;
}
static void os_data_restore (void)
{
    os_data_state = os_data_state_saved;
    os_data_count = os_data_count_saved;
    os_data_addr = os_data_addr_saved;
}
static void bin_data_char (char new_char)
{
    switch (os_data_state) {
    case 0:                 /* data */
        *os_data_addr++ = new_char;
        --os_data_count;
        break;
    }
}
static void set_kerm_bin_mode (unsigned long *addr)
{
    bin_start_address = (char *) addr;
    os_data_init = bin_data_init;
    os_data_char = bin_data_char;
}


/* k_data_* simply handles the kermit escape translations */
static int k_data_escape, k_data_escape_saved;
void k_data_init (void)
{
    k_data_escape = 0;
    os_data_init ();
}
void k_data_save (void)
{
    k_data_escape_saved = k_data_escape;
    os_data_save ();
}
void k_data_restore (void)
{
    k_data_escape = k_data_escape_saved;
    os_data_restore ();
}
void k_data_char (char new_char)
{
    if (k_data_escape) {
        /* last char was escape - translate this character */
        os_data_char (ktrans (new_char));
        k_data_escape = 0;
    } else {
        if (new_char == his_quote) {
            /* this char is escape - remember */
            k_data_escape = 1;
        } else {
            /* otherwise send this char as-is */
            os_data_char (new_char);
        }
    }
}

#define SEND_DATA_SIZE  20
char send_parms[SEND_DATA_SIZE];
char *send_ptr;

/* handle_send_packet interprits the protocol info and builds and
   sends an appropriate ack for what we can do */
void handle_send_packet (int n)
{
    int length = 3;
    int bytes;

    /* initialize some protocol parameters */
    his_eol = END_CHAR;     /* default end of line character */
    his_pad_count = 0;
    his_pad_char = '\0';
    his_quote = K_ESCAPE;

    /* ignore last character if it filled the buffer */
    if (send_ptr == &send_parms[SEND_DATA_SIZE - 1])
        --send_ptr;
    bytes = send_ptr - send_parms;  /* how many bytes we'll process */
    do {
        if (bytes-- <= 0)
            break;
        /* handle MAXL - max length */
        /* ignore what he says - most I'll take (here) is 94 */
        a_b[++length] = tochar (94);
        if (bytes-- <= 0)
            break;
        /* handle TIME - time you should wait for my packets */
        /* ignore what he says - don't wait for my ack longer than 1 second */
        a_b[++length] = tochar (1);
        if (bytes-- <= 0)
            break;
        /* handle NPAD - number of pad chars I need */
        /* remember what he says - I need none */
        his_pad_count = untochar (send_parms[2]);
        a_b[++length] = tochar (0);
        if (bytes-- <= 0)
            break;
        /* handle PADC - pad chars I need */
        /* remember what he says - I need none */
        his_pad_char = ktrans (send_parms[3]);
        a_b[++length] = 0x40;   /* He should ignore this */
        if (bytes-- <= 0)
            break;
        /* handle EOL - end of line he needs */
        /* remember what he says - I need CR */
        his_eol = untochar (send_parms[4]);
        a_b[++length] = tochar (END_CHAR);
        if (bytes-- <= 0)
            break;
        /* handle QCTL - quote control char he'll use */
        /* remember what he says - I'll use '#' */
        his_quote = send_parms[5];
        a_b[++length] = '#';
        if (bytes-- <= 0)
            break;
        /* handle QBIN - 8-th bit prefixing */
        /* ignore what he says - I refuse */
        a_b[++length] = 'N';
        if (bytes-- <= 0)
            break;
        /* handle CHKT - the clock check type */
        /* ignore what he says - I do type 1 (for now) */
        a_b[++length] = '1';
        if (bytes-- <= 0)
            break;
        /* handle REPT - the repeat prefix */
        /* ignore what he says - I refuse (for now) */
        a_b[++length] = 'N';
        if (bytes-- <= 0)
            break;
        /* handle CAPAS - the capabilities mask */
        /* ignore what he says - I only do long packets - I don't do windows */
        a_b[++length] = tochar (2); /* only long packets */
        a_b[++length] = tochar (0); /* no windows */
        a_b[++length] = tochar (94);    /* large packet msb */
        a_b[++length] = tochar (94);    /* large packet lsb */
    } while (0);

    a_b[0] = START_CHAR;
    a_b[1] = tochar (length);
    a_b[2] = tochar (n);
    a_b[3] = ACK_TYPE;
    a_b[++length] = '\0';
    a_b[length] = tochar (chk1 (&a_b[1]));
    a_b[++length] = his_eol;
    a_b[++length] = '\0';
    s1_sendpacket (a_b);
}

/* k_recv receives a OS Open image file over kermit line */
static int k_recv (void)
{
    char new_char;
    char k_state, k_state_saved;
    int sum;
    int done;
    int length;
    int n, last_n;
    int z = 0;
    int len_lo, len_hi;

    /* initialize some protocol parameters */
    his_eol = END_CHAR;     /* default end of line character */
    his_pad_count = 0;
    his_pad_char = '\0';
    his_quote = K_ESCAPE;

    /* initialize the k_recv and k_data state machine */
    done = 0;
    k_state = 0;
    k_data_init ();
    k_state_saved = k_state;
    k_data_save ();
    n = 0;              /* just to get rid of a warning */
    last_n = -1;

    /* expect this "type" sequence (but don't check):
       S: send initiate
       F: file header
       D: data (multiple)
       Z: end of file
       B: break transmission
     */

    /* enter main loop */
    while (!done) {
        /* set the send packet pointer to begining of send packet parms */
        send_ptr = send_parms;

        /* With each packet, start summing the bytes starting with the length.
           Save the current sequence number.
           Note the type of the packet.
           If a character less than SPACE (0x20) is received - error.
         */

#if 0
        /* OLD CODE, Prior to checking sequence numbers */
        /* first have all state machines save current states */
        k_state_saved = k_state;
        k_data_save ();
#endif

        /* get a packet */
        /* wait for the starting character or ^C */
        for (;;) {
            switch (getc ()) {
            case START_CHAR:    /* start packet */
                goto START;
            case ETX_CHAR:      /* ^C waiting for packet */
                return (0);
            default:
                ;
            }
        }
START:
        /* get length of packet */
        sum = 0;
        new_char = getc ();
        if ((new_char & 0xE0) == 0)
            goto packet_error;
        sum += new_char & 0xff;
        length = untochar (new_char);
        /* get sequence number */
        new_char = getc ();
        if ((new_char & 0xE0) == 0)
            goto packet_error;
        sum += new_char & 0xff;
        n = untochar (new_char);
        --length;

        /* NEW CODE - check sequence numbers for retried packets */
        /* Note - this new code assumes that the sequence number is correctly
         * received.  Handling an invalid sequence number adds another layer
         * of complexity that may not be needed - yet!  At this time, I'm hoping
         * that I don't need to buffer the incoming data packets and can write
         * the data into memory in real time.
         */
        if (n == last_n) {
            /* same sequence number, restore the previous state */
            k_state = k_state_saved;
            k_data_restore ();
        } else {
            /* new sequence number, checkpoint the download */
            last_n = n;
            k_state_saved = k_state;
            k_data_save ();
        }
        /* END NEW CODE */

        /* get packet type */
        new_char = getc ();
        if ((new_char & 0xE0) == 0)
            goto packet_error;
        sum += new_char & 0xff;
        k_state = new_char;
        --length;
        /* check for extended length */
        if (length == -2) {
            /* (length byte was 0, decremented twice) */
            /* get the two length bytes */
            new_char = getc ();
            if ((new_char & 0xE0) == 0)
                goto packet_error;
            sum += new_char & 0xff;
            len_hi = untochar (new_char);
            new_char = getc ();
            if ((new_char & 0xE0) == 0)
                goto packet_error;
            sum += new_char & 0xff;
            len_lo = untochar (new_char);
            length = len_hi * 95 + len_lo;
            /* check header checksum */
            new_char = getc ();
            if ((new_char & 0xE0) == 0)
                goto packet_error;
            if (new_char != tochar ((sum + ((sum >> 6) & 0x03)) & 0x3f))
                goto packet_error;
            sum += new_char & 0xff;
/* --length; */ /* new length includes only data and block check to come */
        }
        /* bring in rest of packet */
        while (length > 1) {
            new_char = getc ();
            if ((new_char & 0xE0) == 0)
                goto packet_error;
            sum += new_char & 0xff;
            --length;
            if (k_state == DATA_TYPE) {
                /* pass on the data if this is a data packet */
                k_data_char (new_char);
            } else if (k_state == SEND_TYPE) {
                /* save send pack in buffer as is */
                *send_ptr++ = new_char;
                /* if too much data, back off the pointer */
                if (send_ptr >= &send_parms[SEND_DATA_SIZE])
                    --send_ptr;
            }
        }
        /* get and validate checksum character */
        new_char = getc ();
        if ((new_char & 0xE0) == 0)
            goto packet_error;
        if (new_char != tochar ((sum + ((sum >> 6) & 0x03)) & 0x3f))
            goto packet_error;
        /* get END_CHAR */
        new_char = getc ();
        if (new_char != END_CHAR) {
          packet_error:
            /* restore state machines */
            k_state = k_state_saved;
            k_data_restore ();
            /* send a negative acknowledge packet in */
            send_nack (n);
        } else if (k_state == SEND_TYPE) {
            /* crack the protocol parms, build an appropriate ack packet */
            handle_send_packet (n);
        } else {
            /* send simple acknowledge packet in */
            send_ack (n);
            /* quit if end of transmission */
            if (k_state == BREAK_TYPE)
                done = 1;
        }
        ++z;
    }
    return ((ulong) os_data_addr - (ulong) bin_start_address);
}

static int getcxmodem(void) {
    if (tstc())
        return (getc());
    return -1;
}

/* support xmodem, www.embedsky.net */
static ulong load_serial_xmodem (ulong offset)
{
    int size;
    char buf[32];
    int err;
    int res;
    connection_info_t info;
    char xmodemBuf[1024];
    ulong store_addr = ~0;
    ulong addr = 0;

    size = 0;
    info.mode = xyzModem_xmodem;
    res = xyzModem_stream_open (&info, &err);
    if (!res) {

        while ((res =
            xyzModem_stream_read (xmodemBuf, 1024, &err)) > 0) {
            store_addr = addr + offset;
            size += res;
            addr += res;
#ifndef CFG_NO_FLASH
            if (addr2info (store_addr)) {
                int rc;

                rc = flash_write ((char *) xmodemBuf,
                          store_addr, res);
                if (rc != 0) {
                    flash_perror (rc);
                    return (~0);
                }
            } else
#endif
            {
                memcpy ((char *) (store_addr), xmodemBuf,
                    res);
            }

        }
    } else {
        printf ("%s\n", xyzModem_error (err));
    }

    xyzModem_stream_close (&err);
    xyzModem_stream_terminate (false, &getcxmodem);


    flush_cache (offset, size);

    printf ("## Total Size      = 0x%08x = %d Bytes\n", size, size);
    sprintf (buf, "%X", size);
    setenv ("filesize", buf);

    return offset;
}

static ulong load_serial_ymodem (ulong offset)
{
    int size;
    char buf[32];
    int err;
    int res;
    connection_info_t info;
    char ymodemBuf[1024];
    ulong store_addr = ~0;
    ulong addr = 0;

    size = 0;
    info.mode = xyzModem_ymodem;
    res = xyzModem_stream_open (&info, &err);
    if (!res) {

        while ((res =
            xyzModem_stream_read (ymodemBuf, 1024, &err)) > 0) {
            store_addr = addr + offset;
            size += res;
            addr += res;
#ifndef CFG_NO_FLASH
            if (addr2info (store_addr)) {
                int rc;

                rc = flash_write ((char *) ymodemBuf,
                          store_addr, res);
                if (rc != 0) {
                    flash_perror (rc);
                    return (~0);
                }
            } else
#endif
            {
                memcpy ((char *) (store_addr), ymodemBuf,
                    res);
            }

        }
    } else {
        printf ("%s\n", xyzModem_error (err));
    }

    xyzModem_stream_close (&err);
    xyzModem_stream_terminate (false, &getcxmodem);


    flush_cache (offset, size);

    printf ("## Total Size      = 0x%08x = %d Bytes\n", size, size);
    sprintf (buf, "%X", size);
    setenv ("filesize", buf);

    return offset;
}

#endif  /* CFG_CMD_LOADB */

/* -------------------------------------------------------------------- */

#if (CONFIG_COMMANDS & CFG_CMD_LOADS)

#ifdef  CFG_LOADS_BAUD_CHANGE
U_BOOT_CMD(
    loads, 3, 0,    do_load_serial,
    "loads   - load S-Record file over serial line\n",
    "[ off ] [ baud ]\n"
    "    - load S-Record file over serial line"
    " with offset 'off' and baudrate 'baud'\n"
);

#else   /* ! CFG_LOADS_BAUD_CHANGE */
U_BOOT_CMD(
    loads, 2, 0,    do_load_serial,
    "loads   - load S-Record file over serial line\n",
    "[ off ]\n"
    "    - load S-Record file over serial line with offset 'off'\n"
);
#endif  /* CFG_LOADS_BAUD_CHANGE */

/*
 * SAVES always requires LOADS support, but not vice versa
 */


#if (CONFIG_COMMANDS & CFG_CMD_SAVES)
#ifdef  CFG_LOADS_BAUD_CHANGE
U_BOOT_CMD(
    saves, 4, 0,    do_save_serial,
    "saves   - save S-Record file over serial line\n",
    "[ off ] [size] [ baud ]\n"
    "    - save S-Record file over serial line"
    " with offset 'off', size 'size' and baudrate 'baud'\n"
);
#else   /* ! CFG_LOADS_BAUD_CHANGE */
U_BOOT_CMD(
    saves, 3, 0,    do_save_serial,
    "saves   - save S-Record file over serial line\n",
    "[ off ] [size]\n"
    "    - save S-Record file over serial line with offset 'off' and size 'size'\n"
);
#endif  /* CFG_LOADS_BAUD_CHANGE */
#endif  /* CFG_CMD_SAVES */
#endif  /* CFG_CMD_LOADS */


#if (CONFIG_COMMANDS & CFG_CMD_LOADB)
U_BOOT_CMD(
    loadb, 3, 0,    do_load_serial_bin,
    "loadb   - load binary file over serial line (kermit mode)\n",
    "[ off ] [ baud ]\n"
    "    - load binary file over serial line"
    " with offset 'off' and baudrate 'baud'\n"
);

/* support xmodem, www.embedsky.net */
U_BOOT_CMD(
    loadx, 3, 0,    do_load_serial_bin,
    "loadx   - load binary file over serial line (xmodem mode)\n",
    "[ off ] [ baud ]\n"
    "    - load binary file over serial line"
    " with offset 'off' and baudrate 'baud'\n"
);

U_BOOT_CMD(
    loady, 3, 0,    do_load_serial_bin,
    "loady   - load binary file over serial line (ymodem mode)\n",
    "[ off ] [ baud ]\n"
    "    - load binary file over serial line"
    " with offset 'off' and baudrate 'baud'\n"
);

#endif  /* CFG_CMD_LOADB */

/* -------------------------------------------------------------------- */

#if (CONFIG_COMMANDS & CFG_CMD_HWFLOW)
int do_hwflow (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
{
    extern int hwflow_onoff(int);

    if (argc == 2) {
        if (strcmp(argv[1], "off") == 0)
            hwflow_onoff(-1);
        else
            if (strcmp(argv[1], "on") == 0)
                hwflow_onoff(1);
            else
                printf("Usage: %s\n", cmdtp->usage);
    }
    printf("RTS/CTS hardware flow control: %s\n", hwflow_onoff(0) ? "on" : "off");
    return 0;
}

/* -------------------------------------------------------------------- */

U_BOOT_CMD(
    hwflow, 2, 0,   do_hwflow,
    "hwflow  - turn the harwdare flow control on/off\n",
    "[on|off]\n - change RTS/CTS hardware flow control over serial line\n"
);

#endif /* CFG_CMD_HWFLOW */
